1. Field of the Invention
The present invention relates to a handwritten character input assistant apparatus that ensures and facilitates a blank input when a character string is input by handwritten character pattern recognition in a handwritten character input apparatus that has an input medium of a handwritten character pattern such as a pen-input tablet as in a personal digital assistant (PDA) and does not have an input frame for each character, and a handwritten character input assistant method therefor.
2. Description of the Related Art
Along with the enhancement of a processing speed of a CPU (Central Processing Unit) due to the recent rapid advancement of a computer-related technique, and the like, even in portable computers such as a palmtop computer and a PDA (Personal Digital Assistant), applications capable of recognizing a character pattern input as a handwritten character have become commonplace.
As a method for recognizing a handwritten character pattern, various methods are considered. However, unlike the case of inputting text data through an input medium such as a keyboard, a problem remains unsolved as to how to handle a blank character.
According to the conventional method for recognizing a handwritten character pattern, a blank character is input as follows: first, a special blank symbol is set, a user inputs the special blank symbol as one handwritten character at a position where the user desires to input a blank character, and the special blank symbol is recognized as a blank character at a time of recognition of a handwritten character pattern.
There is also another method in which a blank button for inputting a blank character is set on a keyboard or a screen, and a user inputs a blank character by pressing the blank button at a position where the user desires to input a blank character.
However, according to the method for inserting a special blank symbol, a user is required to input the blank symbol by handwriting, which puts a burden on the user. Alternatively, in the case where a blank symbol is erroneously recognized, it is required to make a correction to erroneous recognition in the same way as in an ordinary handwritten character.
Furthermore, according to the method using a blank button, a user is required to detach a pen-input tablet from a handwritten character input area and press a blank button. This hinders the operation flow of inputting a handwritten character, making a user interface difficult to handle by a user.
In order to solve the above-mentioned problems, a method is considered in which the presence of a blank character is presumed statistically based on the interval of respective characters in a handwritten character pattern input by a user. According to this method, a user intentionally widens the interval between respective handwritten characters at a position where the user desires to input a blank character, whereby the interval between the handwritten characters is recognized as a blank character when the interval is larger than that determined under predetermined conditions at a time of recognition of a handwritten character pattern.
For example, in JP 5(1993)-67237 A, the length of a blank area between handwritten characters in a character string direction is detected, and an appropriate blank character interval is presumed on the line basis, whereby a blank character is inserted in a blank area between handwritten characters having a length in a character string direction larger than a presumed blank character interval.
Furthermore, JP 6(1994)-51900 A discloses a method for detecting the lengths of blank areas between handwritten characters in a character string direction, dividing the detected lengths of the blank areas by a predetermined constant, and inserting blank characters by the number of the obtained quotient.
However, according the above-mentioned method for presuming the presence of a blank character based on the interval of respective characters, determination of what degree of character interval should be recognized as a blank character is minutely varied among users who input handwritten characters. Therefore, there is a possibility that user's feelings may not be matched with the actual recognition.
For example, according to the method disclosed by JP 5(1993)-67237 A, there is no guarantee that the blank character interval presumed on the line basis is matched with that based on user's feelings. Alternatively, according to the method disclosed by JP 6(1994)-51900 A, there is no guarantee that the blank character interval determined by a predetermined constant for division is matched with the blank character interval recognized by a user.
Accordingly, there is a possibility that a blank character is input at a position where a user recognizes as an area for not inputting a blank character, or a blank character is not input at a position where a user desires to input a blank character.